Draw pictures in opposite order.
Draw pictures in opposite order.

As part of r1009 the pictures for a layer are sorted in timestamp order, so
we now need to draw from start to end instead of of end to start.

BUG=trace-viewer:462
R=nduca@chromium.org

Review URL: https://codereview.appspot.com/13486046

git-svn-id: 3a56fcae908c7e16d23cb53443ea4795ac387cf2@1014 0e6d7f2b-9903-5b78-7403-59d27f066143

bpsinc-native/src_third_party_trace-viewer,bpsinc-native/src_third_party_trace-viewer,bpsinc-native/src_third_party_trace-viewer,bpsinc-native/src_third_party_trace-viewer